1. Field of the Invention
The present invention relates to workpiece feed devices and more particularly to so-called feed fingers.
2. Description of the Prior Art
Feed fingers are conventionally used for advancing step-wise into a collet, a workpiece in the form of a long metal bar. The feed finger frictionally grips the bar and advances the bar forwardly into the collet while the collet jaws are open, until the required length of bar projects from the collet. The collet is then closed to rigidly clamp the bar and the feed finger is then retracted along the bar by sliding on the bar by a fixed distance. When the collet jaws are next opened the feed finger is moved forwardly again to index a further portion of the bar through the collet.
Previously proposed feed fingers generally comprise a sleeve-like gripping member which is split by axial slots extending along part of the length of the member. The gripping member, which is mounted on the work bar, is sized for use with one specific cross-sectional size of bar, which means that a different gripping member must be used for each size of the bar which is processed. Examples of such previously proposed feed fingers are described in British patent specifications Nos. 1536 072; 1 529 571; 1 290 965; 1 165 872; and 867 909.
A requirement exists for a feed finger which can be used with different cross-sectional sizes of work bar.